Marine Interpretation Message
Issued by NWS

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AGPN40 KWNM 050226
MIMPAC

MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
726 PM PDT FRI SEP 4 2015

.FORECAST DISCUSSION: MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT
.WEATHER FOR THE NORTH PACIFIC N OF 30N AND E OF 150W.

NO CHANGES ARE PLANNED FOR THE EVENING UPDATE. THE 00Z SFC
ANALYSIS INDICATED HIGH PRES CENTERED NEAR 43N145W WITH RIDGE
EXTENDING E...WITH WEAK TROUGH ALONG CA COAST. THE 18Z GFS IS VERY
CLOSE TO THE PREVIOUS 12Z RUN...ALTHOUGH THE 18Z HAS TRENDED
SLOWER AND A BIT FURTHER N WITH THE TRACK OF REMNANTS OF IGNACIO
NEXT WEEK. THE 18Z RUN IS ACTUALLY NOW VERY CLOSE TO THE
ECMWF WHICH WAS FAVORED BY PREVIOUS SHIFT DURING THIS PERIOD. THE
00Z SEA STATE ANALYSIS INDICATED THAT OBSERVED SEAS WERE WITHIN A
FT OF THE MWW3 FCST VALUES.

-----------------------------------------------------------------
PREVIOUS DISCUSSION...

12Z GUID RMNS IN GOOD AGMRNT THRUT MOST OF THE FCST PERIOD ENDING
WED NGT. WL USE THE 12Z GFS INTO ABT 12Z MON...THEN TREND THE
GRIDS AND TEXT TO THE 12Z ECMWF. EXPLANATION FOLLOWS.

VERY FAMILIAR SYNOPTIC PATTERN TO TAKE SHAPE FOR THE NEXT SVRL
DAYS ACRS THE OFSHR WATERS AS A LOW PRES TROF ALONG THE COAST RMNS
STNRY INTO LATE SAT...BFR STRENGTHENING AND EXPANDING N SUN THRU
WED NGT. MEANWHILE EPAC HIGH PRES WL SLOWLY BUILD E...AND THE
INTERACTION OF THESE TWO FEATURES WL GENERATE SEASONAL N TO NW-LY
WINDS ACRS MOST OF THE OFSHR ZNS. 12Z MODELS STILL INDC SUSTAINED
WINDS SHUD RMN BELOW GALE WARNING CRITERIA.

FARTHER TO THE N...A WK CDFNT WL PASS QUICKLY ACRS THE WA/OR WTRS
SAT NIGHT INTO SUN...BUT INTENSITY/TIMING LOOKS GREAT AMONG GLOB
MDLS. SOME SUGGEST A TRIPLE PT LOW DVLPG IN THE COASTAL WTRS SUN
12Z BUT THIS DOES VERY LITTLE TO AFFECT THE OVRL FCST. STL XPCT
WINDS TO 20 KT ONLY WITH FROPA/NW FLOW BHND FRONT OR WK LOW. 12Z
MON ONWARDS DEFERENCE TO THE 12Z ECMWF OFFERS A BETTER SOLN TO THE
PASSING REMNANTS OF WHAT WL BE POST-TROPICAL IGNACIO. THE 12Z GFS
HAS CONTD ITS SLOWER TREND (AND HAS FOR ITS PAST 4 RUNS)...HWVR
STL RMNS ON THE FASTEST/ERN EDGE OF THE 12Z GLOBAL MODEL ENVELOPE.
REGARDLESS IGNACIO IS XCPTD TO PASS WELL NW THEN N OF THE OFSHR
WTRS...AND IS NOT XCPTD TO SIG RE-INTENSIFY AS A POST-TROPICAL
CYCLONE. ITS ASSCD WK AND DSIPTG CDFNT FCST TO PASS ACRS THE PZ5
RGN WED.

.SEAS...WL USE THE 12Z ENP INTO 12Z MON...THEN TRANSITION FCST TO
12Z WAM ONWARDS. MOST NOTICABLE DIFF WILL BE LATE IN THE FCST
WED WITH THE RESIDUAL SWELL FROM PT IGNACIO. ENP/WW3 HAS A KNOWN
BIAS OF HOLDING ONTO RESIDUAL SWELL A TAD TOO LONG WHICH IS
THE CASE HERE. THE PREFERRED WAM WL DIMINISH SEAS ABT 3-6 HRS
FASTER THAN ENP.

.EXTRATROPICAL STORM SURGE GUIDANCE...N/A



.WARNINGS...PRELIMINARY.

.PZ5 WASHINGTON/OREGON WATERS...
     NONE.

.PZ6 CALIFORNIA WATERS...
     NONE.

$$

.FORECASTER KOSIER/COLLINS. OCEAN PREDICTION CENTER.



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